Provide a means to suppress log-file generation

## Description

GEI verbosely outputs log files of every command, which is great until you realize it outputs for _every_ command. Even trivial commands like `gh gei --help` and `gh gei --version` will generate two log files each.

It would be nice to have a way to tell GEI to _not_ generate those log files. It could be a flag, like `--log-level off`, or an environment variable, like `GEI_LOG_LEVEL=0`.

### Expected Behaviour

```
$ gh gei --log-level=off --version
[2023-09-06 08:32:07] [INFO] You are running the latest version of the gei CLI [v1.1.0]
1.1.0
```